kernel: backport ZTE RNDIS bogus MAC address fix

This is required to support built-in modem of ZTE MF286R, in addition to
other external modems, such as MF831, MF910, MF920, which refuse to
reconfigure their remote MAC address, even if "locally administered" bit
is set, leading to dropped traffic towards the host. Add a workaround
for that issue already present in cdc_ether to rndis_host driver as
well.

Signed-off-by: Lech Perczak <lech.perczak@gmail.com>

6 files changed, 478 insertions, 0 deletions

diff --git a/target/linux/generic/backport-5.10/880-v5.19-cdc_ether-export-usbnet_cdc_zte_rx_fixup.patch b/target/linux/generic/backport-5.10/880-v5.19-cdc_ether-export-usbnet_cdc_zte_rx_fixup.patch
new file mode 100644
index 0000000000..b5a226181e
--- /dev/null
+++ b/target/linux/generic/backport-5.10/880-v5.19-cdc_ether-export-usbnet_cdc_zte_rx_fixup.patch
@@ -0,0 +1,58 @@
+From d91a03b72c5f9c25e5b976f8f67bcf279601d644 Mon Sep 17 00:00:00 2001
+From: Lech Perczak <lech.perczak@gmail.com>
+Date: Fri, 1 Apr 2022 22:03:55 +0200
+Subject: [PATCH 1/3] cdc_ether: export usbnet_cdc_zte_rx_fixup
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Commit bfe9b9d2df66 ("cdc_ether: Improve ZTE MF823/831/910 handling")
+introduces a workaround for certain ZTE modems reporting invalid MAC
+addresses over CDC-ECM.
+The same issue was present on their RNDIS interface,which was fixed in
+commit a5a18bdf7453 ("rndis_host: Set valid random MAC on buggy devices").
+
+However, internal modem of ZTE MF286R router, on its RNDIS interface, also
+exhibits a second issue fixed already in CDC-ECM, of the device not
+respecting configured random MAC address. In order to share the fixup for
+this with rndis_host driver, export the workaround function, which will
+be re-used in the following commit in rndis_host.
+
+Cc: Kristian Evensen <kristian.evensen@gmail.com>
+Cc: Bjørn Mork <bjorn@mork.no>
+Cc: Oliver Neukum <oliver@neukum.org>
+Signed-off-by: Lech Perczak <lech.perczak@gmail.com>
+---
+ drivers/net/usb/cdc_ether.c | 3 ++-
+ include/linux/usb/usbnet.h  | 1 +
+ 2 files changed, 3 insertions(+), 1 deletion(-)
+
+--- a/drivers/net/usb/cdc_ether.c
++++ b/drivers/net/usb/cdc_ether.c
+@@ -466,7 +466,7 @@ static int usbnet_cdc_zte_bind(struct us
+  * device MAC address has been updated). Always set MAC address to that of the
+  * device.
+  */
+-static int usbnet_cdc_zte_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
++int usbnet_cdc_zte_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
+ {
+ 	if (skb->len < ETH_HLEN || !(skb->data[0] & 0x02))
+ 		return 1;
+@@ -476,6 +476,7 @@ static int usbnet_cdc_zte_rx_fixup(struc
+ 
+ 	return 1;
+ }
++EXPORT_SYMBOL_GPL(usbnet_cdc_zte_rx_fixup);
+ 
+ /* Ensure correct link state
+  *
+--- a/include/linux/usb/usbnet.h
++++ b/include/linux/usb/usbnet.h
+@@ -215,6 +215,7 @@ extern int usbnet_ether_cdc_bind(struct
+ extern int usbnet_cdc_bind(struct usbnet *, struct usb_interface *);
+ extern void usbnet_cdc_unbind(struct usbnet *, struct usb_interface *);
+ extern void usbnet_cdc_status(struct usbnet *, struct urb *);
++extern int usbnet_cdc_zte_rx_fixup(struct usbnet *dev, struct sk_buff *skb);
+ 
+ /* CDC and RNDIS support the same host-chosen packet filters for IN transfers */
+ #define	DEFAULT_FILTER	(USB_CDC_PACKET_TYPE_BROADCAST \
diff --git a/target/linux/generic/backport-5.10/881-v5.19-rndis_host-enable-the-bogus-MAC-fixup-for-ZTE-device.patch b/target/linux/generic/backport-5.10/881-v5.19-rndis_host-enable-the-bogus-MAC-fixup-for-ZTE-device.patch
new file mode 100644
index 0000000000..99f0146e50
--- /dev/null
+++ b/target/linux/generic/backport-5.10/881-v5.19-rndis_host-enable-the-bogus-MAC-fixup-for-ZTE-device.patch
@@ -0,0 +1,118 @@
+From 69a9efb689b43fedf5f19431f1889aa6b8d35d55 Mon Sep 17 00:00:00 2001
+From: Lech Perczak <lech.perczak@gmail.com>
+Date: Fri, 1 Apr 2022 22:04:01 +0200
+Subject: [PATCH 2/3] rndis_host: enable the bogus MAC fixup for ZTE devices
+ from cdc_ether
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Certain ZTE modems, namely: MF823. MF831, MF910, built-in modem from
+MF286R, expose both CDC-ECM and RNDIS network interfaces.
+They have a trait of ignoring the locally-administered MAC address
+configured on the interface both in CDC-ECM and RNDIS part,
+and this leads to dropping of incoming traffic by the host.
+However, the workaround was only present in CDC-ECM, and MF286R
+explicitly requires it in RNDIS mode.
+
+Re-use the workaround in rndis_host as well, to fix operation of MF286R
+module, some versions of which expose only the RNDIS interface. Do so by
+introducing new flag, RNDIS_DRIVER_DATA_DST_MAC_FIXUP, and testing for it
+in rndis_rx_fixup. This is required, as RNDIS uses frame batching, and all
+of the packets inside the batch need the fixup. This might introduce a
+performance penalty, because test is done for every returned Ethernet
+frame.
+
+Apply the workaround to both "flavors" of RNDIS interfaces, as older ZTE
+modems, like MF823 found in the wild, report the USB_CLASS_COMM class
+interfaces, while MF286R reports USB_CLASS_WIRELESS_CONTROLLER.
+
+Suggested-by: Bjørn Mork <bjorn@mork.no>
+Cc: Kristian Evensen <kristian.evensen@gmail.com>
+Cc: Oliver Neukum <oliver@neukum.org>
+Signed-off-by: Lech Perczak <lech.perczak@gmail.com>
+---
+ drivers/net/usb/rndis_host.c   | 32 ++++++++++++++++++++++++++++++++
+ include/linux/usb/rndis_host.h |  1 +
+ 2 files changed, 33 insertions(+)
+
+--- a/drivers/net/usb/rndis_host.c
++++ b/drivers/net/usb/rndis_host.c
+@@ -485,10 +485,14 @@ EXPORT_SYMBOL_GPL(rndis_unbind);
+  */
+ int rndis_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
+ {
++	bool dst_mac_fixup;
++
+ 	/* This check is no longer done by usbnet */
+ 	if (skb->len < dev->net->hard_header_len)
+ 		return 0;
+ 
++	dst_mac_fixup = !!(dev->driver_info->data & RNDIS_DRIVER_DATA_DST_MAC_FIXUP);
++
+ 	/* peripheral may have batched packets to us... */
+ 	while (likely(skb->len)) {
+ 		struct rndis_data_hdr	*hdr = (void *)skb->data;
+@@ -523,10 +527,17 @@ int rndis_rx_fixup(struct usbnet *dev, s
+ 			break;
+ 		skb_pull(skb, msg_len - sizeof *hdr);
+ 		skb_trim(skb2, data_len);
++
++		if (unlikely(dst_mac_fixup))
++			usbnet_cdc_zte_rx_fixup(dev, skb2);
++
+ 		usbnet_skb_return(dev, skb2);
+ 	}
+ 
+ 	/* caller will usbnet_skb_return the remaining packet */
++	if (unlikely(dst_mac_fixup))
++		usbnet_cdc_zte_rx_fixup(dev, skb);
++
+ 	return 1;
+ }
+ EXPORT_SYMBOL_GPL(rndis_rx_fixup);
+@@ -600,6 +611,17 @@ static const struct driver_info	rndis_po
+ 	.tx_fixup =	rndis_tx_fixup,
+ };
+ 
++static const struct driver_info	zte_rndis_info = {
++	.description =	"ZTE RNDIS device",
++	.flags =	FLAG_ETHER | FLAG_POINTTOPOINT | FLAG_FRAMING_RN | FLAG_NO_SETINT,
++	.data =		RNDIS_DRIVER_DATA_DST_MAC_FIXUP,
++	.bind =		rndis_bind,
++	.unbind =	rndis_unbind,
++	.status =	rndis_status,
++	.rx_fixup =	rndis_rx_fixup,
++	.tx_fixup =	rndis_tx_fixup,
++};
++
+ /*-------------------------------------------------------------------------*/
+ 
+ static const struct usb_device_id	products [] = {
+@@ -609,6 +631,16 @@ static const struct usb_device_id	produc
+ 				      USB_CLASS_COMM, 2 /* ACM */, 0x0ff),
+ 	.driver_info = (unsigned long) &rndis_poll_status_info,
+ }, {
++	/* ZTE WWAN modules */
++	USB_VENDOR_AND_INTERFACE_INFO(0x19d2,
++				      USB_CLASS_WIRELESS_CONTROLLER, 1, 3),
++	.driver_info = (unsigned long)&zte_rndis_info,
++}, {
++	/* ZTE WWAN modules, ACM flavour */
++	USB_VENDOR_AND_INTERFACE_INFO(0x19d2,
++				      USB_CLASS_COMM, 2 /* ACM */, 0x0ff),
++	.driver_info = (unsigned long)&zte_rndis_info,
++}, {
+ 	/* Hytera Communications DMR radios' "Radio to PC Network" */
+ 	USB_VENDOR_AND_INTERFACE_INFO(0x238b,
+ 				      USB_CLASS_COMM, 2 /* ACM */, 0x0ff),
+--- a/include/linux/usb/rndis_host.h
++++ b/include/linux/usb/rndis_host.h
+@@ -197,6 +197,7 @@ struct rndis_keepalive_c {	/* IN (option
+ 
+ /* Flags for driver_info::data */
+ #define RNDIS_DRIVER_DATA_POLL_STATUS	1	/* poll status before control */
++#define RNDIS_DRIVER_DATA_DST_MAC_FIXUP	2	/* device ignores configured MAC address */
+ 
+ extern void rndis_status(struct usbnet *dev, struct urb *urb);
+ extern int
diff --git a/target/linux/generic/backport-5.10/882-v5.19-rndis_host-limit-scope-of-bogus-MAC-address-detectio.patch b/target/linux/generic/backport-5.10/882-v5.19-rndis_host-limit-scope-of-bogus-MAC-address-detectio.patch
new file mode 100644
index 0000000000..bdb78ff170
--- /dev/null
+++ b/target/linux/generic/backport-5.10/882-v5.19-rndis_host-limit-scope-of-bogus-MAC-address-detectio.patch
@@ -0,0 +1,63 @@
+From 1bfbe1799b9ec5d00f7f032d6e7db1980e466aeb Mon Sep 17 00:00:00 2001
+From: Lech Perczak <lech.perczak@gmail.com>
+Date: Sat, 2 Apr 2022 02:19:57 +0200
+Subject: [PATCH 3/3] rndis_host: limit scope of bogus MAC address detection to
+ ZTE devices
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Reporting of bogus MAC addresses and ignoring configuration of new
+destination address wasn't observed outside of a range of ZTE devices,
+among which this seems to be the common bug. Align rndis_host driver
+with implementation found in cdc_ether, which also limits this workaround
+to ZTE devices.
+
+Suggested-by: Bjørn Mork <bjorn@mork.no>
+Cc: Kristian Evensen <kristian.evensen@gmail.com>
+Cc: Oliver Neukum <oliver@neukum.org>
+Signed-off-by: Lech Perczak <lech.perczak@gmail.com>
+---
+ drivers/net/usb/rndis_host.c | 17 ++++++++++++-----
+ 1 file changed, 12 insertions(+), 5 deletions(-)
+
+--- a/drivers/net/usb/rndis_host.c
++++ b/drivers/net/usb/rndis_host.c
+@@ -418,10 +418,7 @@ generic_rndis_bind(struct usbnet *dev, s
+ 		goto halt_fail_and_release;
+ 	}
+ 
+-	if (bp[0] & 0x02)
+-		eth_hw_addr_random(net);
+-	else
+-		ether_addr_copy(net->dev_addr, bp);
++	ether_addr_copy(net->dev_addr, bp);
+ 
+ 	/* set a nonzero filter to enable data transfers */
+ 	memset(u.set, 0, sizeof *u.set);
+@@ -463,6 +460,16 @@ static int rndis_bind(struct usbnet *dev
+ 	return generic_rndis_bind(dev, intf, FLAG_RNDIS_PHYM_NOT_WIRELESS);
+ }
+ 
++static int zte_rndis_bind(struct usbnet *dev, struct usb_interface *intf)
++{
++	int status = rndis_bind(dev, intf);
++
++	if (!status && (dev->net->dev_addr[0] & 0x02))
++		eth_hw_addr_random(dev->net);
++
++	return status;
++}
++
+ void rndis_unbind(struct usbnet *dev, struct usb_interface *intf)
+ {
+ 	struct rndis_halt	*halt;
+@@ -615,7 +622,7 @@ static const struct driver_info	zte_rndi
+ 	.description =	"ZTE RNDIS device",
+ 	.flags =	FLAG_ETHER | FLAG_POINTTOPOINT | FLAG_FRAMING_RN | FLAG_NO_SETINT,
+ 	.data =		RNDIS_DRIVER_DATA_DST_MAC_FIXUP,
+-	.bind =		rndis_bind,
++	.bind =		zte_rndis_bind,
+ 	.unbind =	rndis_unbind,
+ 	.status =	rndis_status,
+ 	.rx_fixup =	rndis_rx_fixup,
diff --git a/target/linux/generic/backport-5.15/880-v5.19-cdc_ether-export-usbnet_cdc_zte_rx_fixup.patch b/target/linux/generic/backport-5.15/880-v5.19-cdc_ether-export-usbnet_cdc_zte_rx_fixup.patch
new file mode 100644
index 0000000000..39fdb32773
--- /dev/null
+++ b/target/linux/generic/backport-5.15/880-v5.19-cdc_ether-export-usbnet_cdc_zte_rx_fixup.patch
@@ -0,0 +1,58 @@
+From a79a5613e1907e1bf09bb6ba6fd5ff43b66c1afe Mon Sep 17 00:00:00 2001
+From: Lech Perczak <lech.perczak@gmail.com>
+Date: Fri, 1 Apr 2022 22:03:55 +0200
+Subject: [PATCH 1/3] cdc_ether: export usbnet_cdc_zte_rx_fixup
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Commit bfe9b9d2df66 ("cdc_ether: Improve ZTE MF823/831/910 handling")
+introduces a workaround for certain ZTE modems reporting invalid MAC
+addresses over CDC-ECM.
+The same issue was present on their RNDIS interface,which was fixed in
+commit a5a18bdf7453 ("rndis_host: Set valid random MAC on buggy devices").
+
+However, internal modem of ZTE MF286R router, on its RNDIS interface, also
+exhibits a second issue fixed already in CDC-ECM, of the device not
+respecting configured random MAC address. In order to share the fixup for
+this with rndis_host driver, export the workaround function, which will
+be re-used in the following commit in rndis_host.
+
+Cc: Kristian Evensen <kristian.evensen@gmail.com>
+Cc: Bjørn Mork <bjorn@mork.no>
+Cc: Oliver Neukum <oliver@neukum.org>
+Signed-off-by: Lech Perczak <lech.perczak@gmail.com>
+---
+ drivers/net/usb/cdc_ether.c | 3 ++-
+ include/linux/usb/usbnet.h  | 1 +
+ 2 files changed, 3 insertions(+), 1 deletion(-)
+
+--- a/drivers/net/usb/cdc_ether.c
++++ b/drivers/net/usb/cdc_ether.c
+@@ -479,7 +479,7 @@ static int usbnet_cdc_zte_bind(struct us
+  * device MAC address has been updated). Always set MAC address to that of the
+  * device.
+  */
+-static int usbnet_cdc_zte_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
++int usbnet_cdc_zte_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
+ {
+ 	if (skb->len < ETH_HLEN || !(skb->data[0] & 0x02))
+ 		return 1;
+@@ -489,6 +489,7 @@ static int usbnet_cdc_zte_rx_fixup(struc
+ 
+ 	return 1;
+ }
++EXPORT_SYMBOL_GPL(usbnet_cdc_zte_rx_fixup);
+ 
+ /* Ensure correct link state
+  *
+--- a/include/linux/usb/usbnet.h
++++ b/include/linux/usb/usbnet.h
+@@ -214,6 +214,7 @@ extern int usbnet_ether_cdc_bind(struct
+ extern int usbnet_cdc_bind(struct usbnet *, struct usb_interface *);
+ extern void usbnet_cdc_unbind(struct usbnet *, struct usb_interface *);
+ extern void usbnet_cdc_status(struct usbnet *, struct urb *);
++extern int usbnet_cdc_zte_rx_fixup(struct usbnet *dev, struct sk_buff *skb);
+ 
+ /* CDC and RNDIS support the same host-chosen packet filters for IN transfers */
+ #define	DEFAULT_FILTER	(USB_CDC_PACKET_TYPE_BROADCAST \
diff --git a/target/linux/generic/backport-5.15/881-v5.19-rndis_host-enable-the-bogus-MAC-fixup-for-ZTE-device.patch b/target/linux/generic/backport-5.15/881-v5.19-rndis_host-enable-the-bogus-MAC-fixup-for-ZTE-device.patch
new file mode 100644
index 0000000000..7da2280cd9
--- /dev/null
+++ b/target/linux/generic/backport-5.15/881-v5.19-rndis_host-enable-the-bogus-MAC-fixup-for-ZTE-device.patch
@@ -0,0 +1,118 @@
+From aa8aff10e969aca0cb64f5e54ff7489355582667 Mon Sep 17 00:00:00 2001
+From: Lech Perczak <lech.perczak@gmail.com>
+Date: Fri, 1 Apr 2022 22:04:01 +0200
+Subject: [PATCH 2/3] rndis_host: enable the bogus MAC fixup for ZTE devices
+ from cdc_ether
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Certain ZTE modems, namely: MF823. MF831, MF910, built-in modem from
+MF286R, expose both CDC-ECM and RNDIS network interfaces.
+They have a trait of ignoring the locally-administered MAC address
+configured on the interface both in CDC-ECM and RNDIS part,
+and this leads to dropping of incoming traffic by the host.
+However, the workaround was only present in CDC-ECM, and MF286R
+explicitly requires it in RNDIS mode.
+
+Re-use the workaround in rndis_host as well, to fix operation of MF286R
+module, some versions of which expose only the RNDIS interface. Do so by
+introducing new flag, RNDIS_DRIVER_DATA_DST_MAC_FIXUP, and testing for it
+in rndis_rx_fixup. This is required, as RNDIS uses frame batching, and all
+of the packets inside the batch need the fixup. This might introduce a
+performance penalty, because test is done for every returned Ethernet
+frame.
+
+Apply the workaround to both "flavors" of RNDIS interfaces, as older ZTE
+modems, like MF823 found in the wild, report the USB_CLASS_COMM class
+interfaces, while MF286R reports USB_CLASS_WIRELESS_CONTROLLER.
+
+Suggested-by: Bjørn Mork <bjorn@mork.no>
+Cc: Kristian Evensen <kristian.evensen@gmail.com>
+Cc: Oliver Neukum <oliver@neukum.org>
+Signed-off-by: Lech Perczak <lech.perczak@gmail.com>
+---
+ drivers/net/usb/rndis_host.c   | 32 ++++++++++++++++++++++++++++++++
+ include/linux/usb/rndis_host.h |  1 +
+ 2 files changed, 33 insertions(+)
+
+--- a/drivers/net/usb/rndis_host.c
++++ b/drivers/net/usb/rndis_host.c
+@@ -485,10 +485,14 @@ EXPORT_SYMBOL_GPL(rndis_unbind);
+  */
+ int rndis_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
+ {
++	bool dst_mac_fixup;
++
+ 	/* This check is no longer done by usbnet */
+ 	if (skb->len < dev->net->hard_header_len)
+ 		return 0;
+ 
++	dst_mac_fixup = !!(dev->driver_info->data & RNDIS_DRIVER_DATA_DST_MAC_FIXUP);
++
+ 	/* peripheral may have batched packets to us... */
+ 	while (likely(skb->len)) {
+ 		struct rndis_data_hdr	*hdr = (void *)skb->data;
+@@ -523,10 +527,17 @@ int rndis_rx_fixup(struct usbnet *dev, s
+ 			break;
+ 		skb_pull(skb, msg_len - sizeof *hdr);
+ 		skb_trim(skb2, data_len);
++
++		if (unlikely(dst_mac_fixup))
++			usbnet_cdc_zte_rx_fixup(dev, skb2);
++
+ 		usbnet_skb_return(dev, skb2);
+ 	}
+ 
+ 	/* caller will usbnet_skb_return the remaining packet */
++	if (unlikely(dst_mac_fixup))
++		usbnet_cdc_zte_rx_fixup(dev, skb);
++
+ 	return 1;
+ }
+ EXPORT_SYMBOL_GPL(rndis_rx_fixup);
+@@ -600,6 +611,17 @@ static const struct driver_info	rndis_po
+ 	.tx_fixup =	rndis_tx_fixup,
+ };
+ 
++static const struct driver_info	zte_rndis_info = {
++	.description =	"ZTE RNDIS device",
++	.flags =	FLAG_ETHER | FLAG_POINTTOPOINT | FLAG_FRAMING_RN | FLAG_NO_SETINT,
++	.data =		RNDIS_DRIVER_DATA_DST_MAC_FIXUP,
++	.bind =		rndis_bind,
++	.unbind =	rndis_unbind,
++	.status =	rndis_status,
++	.rx_fixup =	rndis_rx_fixup,
++	.tx_fixup =	rndis_tx_fixup,
++};
++
+ /*-------------------------------------------------------------------------*/
+ 
+ static const struct usb_device_id	products [] = {
+@@ -614,6 +636,16 @@ static const struct usb_device_id	produc
+ 				      USB_CLASS_COMM, 2 /* ACM */, 0x0ff),
+ 	.driver_info = (unsigned long)&rndis_info,
+ }, {
++	/* ZTE WWAN modules */
++	USB_VENDOR_AND_INTERFACE_INFO(0x19d2,
++				      USB_CLASS_WIRELESS_CONTROLLER, 1, 3),
++	.driver_info = (unsigned long)&zte_rndis_info,
++}, {
++	/* ZTE WWAN modules, ACM flavour */
++	USB_VENDOR_AND_INTERFACE_INFO(0x19d2,
++				      USB_CLASS_COMM, 2 /* ACM */, 0x0ff),
++	.driver_info = (unsigned long)&zte_rndis_info,
++}, {
+ 	/* RNDIS is MSFT's un-official variant of CDC ACM */
+ 	USB_INTERFACE_INFO(USB_CLASS_COMM, 2 /* ACM */, 0x0ff),
+ 	.driver_info = (unsigned long) &rndis_info,
+--- a/include/linux/usb/rndis_host.h
++++ b/include/linux/usb/rndis_host.h
+@@ -197,6 +197,7 @@ struct rndis_keepalive_c {	/* IN (option
+ 
+ /* Flags for driver_info::data */
+ #define RNDIS_DRIVER_DATA_POLL_STATUS	1	/* poll status before control */
++#define RNDIS_DRIVER_DATA_DST_MAC_FIXUP	2	/* device ignores configured MAC address */
+ 
+ extern void rndis_status(struct usbnet *dev, struct urb *urb);
+ extern int
diff --git a/target/linux/generic/backport-5.15/882-v5.19-rndis_host-limit-scope-of-bogus-MAC-address-detectio.patch b/target/linux/generic/backport-5.15/882-v5.19-rndis_host-limit-scope-of-bogus-MAC-address-detectio.patch
new file mode 100644
index 0000000000..ebe7a43fd3
--- /dev/null
+++ b/target/linux/generic/backport-5.15/882-v5.19-rndis_host-limit-scope-of-bogus-MAC-address-detectio.patch
@@ -0,0 +1,63 @@
+From 9bfb4bcda7ba32d73ea322ea56a8ebe32e9247f6 Mon Sep 17 00:00:00 2001
+From: Lech Perczak <lech.perczak@gmail.com>
+Date: Sat, 2 Apr 2022 02:19:57 +0200
+Subject: [PATCH 3/3] rndis_host: limit scope of bogus MAC address detection to
+ ZTE devices
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Reporting of bogus MAC addresses and ignoring configuration of new
+destination address wasn't observed outside of a range of ZTE devices,
+among which this seems to be the common bug. Align rndis_host driver
+with implementation found in cdc_ether, which also limits this workaround
+to ZTE devices.
+
+Suggested-by: Bjørn Mork <bjorn@mork.no>
+Cc: Kristian Evensen <kristian.evensen@gmail.com>
+Cc: Oliver Neukum <oliver@neukum.org>
+Signed-off-by: Lech Perczak <lech.perczak@gmail.com>
+---
+ drivers/net/usb/rndis_host.c | 17 ++++++++++++-----
+ 1 file changed, 12 insertions(+), 5 deletions(-)
+
+--- a/drivers/net/usb/rndis_host.c
++++ b/drivers/net/usb/rndis_host.c
+@@ -418,10 +418,7 @@ generic_rndis_bind(struct usbnet *dev, s
+ 		goto halt_fail_and_release;
+ 	}
+ 
+-	if (bp[0] & 0x02)
+-		eth_hw_addr_random(net);
+-	else
+-		ether_addr_copy(net->dev_addr, bp);
++	ether_addr_copy(net->dev_addr, bp);
+ 
+ 	/* set a nonzero filter to enable data transfers */
+ 	memset(u.set, 0, sizeof *u.set);
+@@ -463,6 +460,16 @@ static int rndis_bind(struct usbnet *dev
+ 	return generic_rndis_bind(dev, intf, FLAG_RNDIS_PHYM_NOT_WIRELESS);
+ }
+ 
++static int zte_rndis_bind(struct usbnet *dev, struct usb_interface *intf)
++{
++	int status = rndis_bind(dev, intf);
++
++	if (!status && (dev->net->dev_addr[0] & 0x02))
++		eth_hw_addr_random(dev->net);
++
++	return status;
++}
++
+ void rndis_unbind(struct usbnet *dev, struct usb_interface *intf)
+ {
+ 	struct rndis_halt	*halt;
+@@ -615,7 +622,7 @@ static const struct driver_info	zte_rndi
+ 	.description =	"ZTE RNDIS device",
+ 	.flags =	FLAG_ETHER | FLAG_POINTTOPOINT | FLAG_FRAMING_RN | FLAG_NO_SETINT,
+ 	.data =		RNDIS_DRIVER_DATA_DST_MAC_FIXUP,
+-	.bind =		rndis_bind,
++	.bind =		zte_rndis_bind,
+ 	.unbind =	rndis_unbind,
+ 	.status =	rndis_status,
+ 	.rx_fixup =	rndis_rx_fixup,